CVE-2026-5450
Description
A flaw was found in glibc (GNU C Library). This vulnerability occurs when an application uses the scanf family of functions with a %mc format specifier, which is used for dynamically allocating memory for character input, and provides an explicit width greater than 1024. This specific combination can lead to a one-byte heap buffer overflow, potentially allowing an attacker to corrupt memory.
Statement
Because this flaw requires that an affected application call the affected functions with an attacker-supplied value, Red Hat assesses the Attack Complexity of this flaw as High. Additionally, the flaw overflows a single byte onto the heap, so meaningful exploitation requires that the heap is structured such that a single byte can lead to an attacker-controlled outcome, or that the affected functions can be invoked with an attacker-controlled buffer base address. Regarding Attack Vector and Privileges Required, Red Hat assesses these elements as Local and Low respectively, as remote unauthenticated exploitation would require all the conditions above in a library client that listened on a network port and processed attacker-controllable data with the affected library functions.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5 | N/A | 9.8 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | High | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | Required | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | Low | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Availability,Confidentiality
Technical Impact: DoS: Crash, Exit, or Restart; Execute Unauthorized Code or Commands; Read Memory; Modify Memory
If the incorrect calculation is used in the context of memory allocation, then the software may create a buffer that is smaller or larger than expected. If the allocated buffer is smaller than expected, this could lead to an out-of-bounds read or write (CWE-119), possibly causing a crash, allowing arbitrary code execution, or exposing sensitive data.
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